I'm not savvy with the interior of the TSX, but I did manage to fit our
Britax Wizard/
Boulevard in a 2001 F150 extended cab -- my child was over 1 year old & could sit quite upright, though & I needed to move the front passenger seat forward.... (I sat in the back with kiddo)
What age is your child? If your child is young enough to require the full 45 degree recline angle then you may need to look into disabling the passenger airbag to insta0ll the seat in front

(all other passengers would then need to sit in the back